When forming a refrigerator cabinet with a foamed thermal insulation material such as urethane between the inner liner and the outer casing, the foam is introduced as a liquid into the space between the liner and the casing and foams into place by adhering to both the outer surface of the liner and the inner surface of the casing. During this formation of the refrigerator cabinet, a foam plug is disposed within the liner in spaced relation thereto to have a predetermined clearance therebetween. This predetermined clearance is necessary because of tolerance variations of the vacuum formed inner liner.
During foaming of urethane, a pressure of about 3-5 p.s.i. is exerted against the outer surface of the liner. As the thickness of the liner decreases, the pressure exerted during foaming causes movement of the inner surface of the liner against the foam plug. Since the liner is vacuum formed, its corners previously have been produced on a spherical radius. As the thickness of the liner decreases, the slight pressure created by foaming of the thermal insulation material can cause deformation of the liner so that it is pushed against the foam plug. As the pressure increases, increase thicknesses of the liner can be pushed against the foam plug.
When the liner has its inner surface pushed by the foaming pressure against the foam plug, there will be buckling of each corner of the inner liner having a spherical radius. This occurs because a portion of the liner at each corner with the spherical radius is placed in compression when moved against a corresponding surface of the foam plug. This compression of each corner of the liner seeks to increase the total distance of the corner, and this is not possible so that the corner buckles. This produces a crinkling effect, which is aesthetically undesirable.